1. Field of the Invention
The present invention relates to an image processing device and, more particularly, to an image processing device including filtering means for enhancing image quality with an input image signal.
2. Discussion of the Background
Japanese Patent Laid-Open Publication No. 61-66472 discloses a filter having a smoothing circuit and an edge enhancing circuit connected in series. To render the degree of edges included in a pattern variable, the filter taught in this document smooths an image signal undergone shading correction, and again performs smoothing and edge enhancement with the smoothed signal so as to produce a linear sum.
The problem with the above conventional filter is that the degree of edge enhancement of characters and lines cannot be adjusted in the main and subscanning directions individually. Such a filter is not applicable to an image processing device of the type varying magnification in the subscanning direction by varying the running speed of the carriage of a scanner, unless the overall filer coefficient is replaced. Further, when it comes to a digital copier capable of varying magnification between 25% and 400%, the conventional filter must be provided with a plurality of filter coefficients, scaling up hardware.